Environmental assessment of air to water machines - triangulation to manage scope uncertainty

Purpose: Devices that condense and disinfect water vapour to provide chilled drinking water in office environments, so-called air water generators (AWGs), are being marketed as environmentally friendly alternatives to the traditional bottled water cooler. We sought to examine this claim. Methods: The approach adopted was a preliminary life cycle assessment with performance indicators for the use of energy and water and the emission of greenhouse gases. We compared an AWG with its main market competitor, the traditional bottled water cooler and a simple refrigerator containing a jug of water. Modelling was based on Australian conditions and energy supply. To manage possible scope uncertainty, we borrowed the idea of triangulation as defined in the social sciences. Results and discussion: We found that without a renewable energy supply, the claim of environmental superiority is not supported by quantitative analysis. For each indicator, the AWG s score was typically two to four times higher than the alternatives. Energy consumption was the key issue driving all three indicators. Conclusions: Considering the principal environmental issues related to these systems, air-to-water machines significantly underperform bottled water coolers. A simple refrigerator has the capacity to perform multiple functions and therefore outperform both the bottled and atmospheric water options once allocation of burdens is considered. These conclusions are supported by all three perspectives examined to manage uncertainty.